Means for knitting elastic tubes



Aug. 13, 1940. E, FLEER MEANs Foa KNITTING ELAsTrc TUBES Filed April 20, 1958 l I I INVENTOR EGBER-r -Les BY l l mu@ y ATTORNEY Patented Aug. 13, 1940 UNlTED STATES lATENT FFlCE 2 Claims.

My invention relates to improvements in means for knitting elastic tubes, including an improved method of interlacing elastic threads between the loops of the knitted material, and improved apparatus to facilitate the practice of the method.

The object of my invention is .to provide dependable means for laying in the elastic thread between the loops formed by the cylinder needles and those formed by the dial needles of a circular knitting machine, whereby the thread may be held to the groove formed between the two sets of loops until anchored therein by superposed loops of knitted yarn.

In accordance with well known practice, when laying in elastic thread, such thread is fed through a guide which travels a circular path concentric to the cylinder of a tubular knitting machine, and after the thread has been anchored by a few cylinder needles the guide delivers the thread along a line substantially concentric to the top of the cylinder and in a position to be cast off with the yarn loops previously formed by the cylinder needles. As these needles progressively form new stitch loops their latches are closed and their previously formed loops cast off with the unlooped elastic thread, the latter being intended to be received in the groove between these loops and the rib stitched loops formed by the dial needles.

But heretofore no means were known for preventing the elastic thread from occasionally rising above the level of the dial needles and being caught thereby instead of being deposited in a position for interlacing between the rib stitched loops. When this occurs, the thread becomes entangled with the needles and some or all of the needles are apt to become broken before the machine can be stopped. My object is to provide means for preventing such accidents.

In the accompanying drawing:

Figure 1 is a plan View of a circular knitting machine dial, with the dial cap removed, but showing a set of dial cams, including my improved center cam, and also showing the rotary guide carrier with its yarn feeding guide and auxiliary guide for feeding elastic thread.

Figure 2 is a diagrammatic development of the cylinder and cylinder needles of a circular knitting machine, showing the traveling guides in their relation to each other, and With portions broken away.

Like parts are identified by the same reference characters throughout the several views.

In my improved method, the yarn is fed through the traveling yarn guide I0 and stitched bythe cylinder needles II and dial needles I2 in the ordinary manner.

The center cam I3 is of ordinary construction, with the exception of an added cam projection I4, which, for the sake of clearness, I have illustrated as an attachment for the center cam, although it will preferably be formed integrally therewith. This cam projection is located immediately in the rear of the stitch forming recess I5. The stitch cam I 6 is of ordinary type, with a stitch forming projection I 'I opposed to the recess I5, whereby registering dial needles are retracted while the projection I'I is moving in contact with their butts. In the construction illustrated, the dial I8 and cylinder I9 are stationary. The carrier 26, the cams and yarn feeding guide, rotate, the dial cams being supported by an ordinary dial cap 2I, a fragment of which is illustrated in Figure 1.

The threads of yarn, looped to form the ordinary wales of knitted material, are substantially inelastic, and when stretched they tend to retain the distended form after the tension yhas been relieved. Therefore, when a resilient fabric is desired, an elastic thread islaid in between the loops as a resilient element to contract the tubular fabric after distention.

When elastic thread is to be laid in, it is fed through a thread guide 25, supported from the carrier 20 in a position to follow the yarn feeding guide, as illustrated in Figure 1. The thread is delivered along a line concentric with the top of the cylinder and substantially at the level occupied by the yarn loops on the shanks of the cylinder needles after they have been released from the hooks. Therefore, during a stitching operation, as the cylinder needles are drawn down to form new loops, their latches are closed and the old loops, together with the contiguous unlooped elastic thread, are cast olf and drawn over the top of the cylinder.

Between the point where the elastic thread is being cast off with the previously formed loops, and the point where the elastic thread is being fed in by the following thread guide, I utilize the cam projection I4 to advance the dial needles radially to a sufficient extent to prevent the elastic thread from lifting above the level of these needles, rthis being the area where entanglement of the thread with the needles has heretofore occurred.

While I prefer to employ the dial needles occupying this area to hold the elastic thread to a plane below the needles, I do not limit the scope of my invention to the particular means disclosed, since any means for interposing barriers to the lifting thread will accomplish my purpose. However, the use of the cam projection I4 enables me to utilize the dial needles and hold the thread in its proper horizontal plane without the necessity of providing further holding means, manually or otherwise operative.

The auxiliary cam projection I4 merely advances the dial needles far enough to bridge the gap between the dial and the cylinder and thus prevent the cast 01T elastic thread from lifting or buckling upwardly above the plane in which these needles operate.

In the area immediately back of the traveling stitch cams the cylinder needles and also the dial needles are retracted, and as the cast off elastic thread moves inwardly over the margin of the cylinder to an arc of a smaller circle, its tension slackens, and unless it is promptly covered by the dial needles portions of it may rise above their level.

However, the cam projection- Ill does not advance the dial needles far enough to interfere with the feeding operation of the following thread guide 25.

By my improved method the elastic thread is fed to the outer side of the cylinder and cylinder needle shanks from the point of initial engagement with the cylinder needles, as indicated in Figure l, and is held in position under its own tension as it encircles the cylinder. In the meantime the yarn guide I8 is feeding the yarn into position for engagement by the cylinder needle hooks, such engagement taking place above the plane occupied by the elastic thread. When the yarn guide I has encircled the cylinder and commences its travel along the elastic thread which has previously been fed to the outer side of the cylinder needle Shanks as above described, then the depression of the cylinder needles to form new loops and cast oiT the old loops also allows the unlooped elastic thread to cast off with the yarn and normally pass downwardly in the clearance space between the cylinder and dial.

But in so doing the elastic thread occupies a position in a smaller circle than that whichits other portions ocupy when outside of the cylinder needles, and since it is not under tension such as would cause it to take up the slack, it tends to buckle, and occasionally tends to buckle in an upward direction above the plane of the dial needles. The cam projection I 4 prevents the buckling elastic thread from passing above the plane of the dial needles by advancing the dial needles over the above mentioned gap between the verge of the dial and the verge of the cylinder, and therefore the dial needles are made to hold the thread in the cast off position immediately after the casting off operation and 'prior to the time that it can be held in position by the cast off dial loops.

I claim:

1.The method of interlacing elastic thread between rib-stitched loops of a tubular fabric in process of being knitted on a cylindrical knitting machine, which consists in feeding an elastic thread along a line substantially concentric with the top of the cylinder, simultaneously feeding substantially inelastic yarn thread to the cylinder and dial needles at an arcuately distant point, and advancing dial needles to a thread covering position immediately in the rear of those employed for stitching purposes and before the slackened tension of the cast off elastic thread permits of its elevation above the level of the dial needles, whereby the elastic thread may be cast on with the yarn loops without entanglement with the dial needles.

2. In a circular knitting machine having a needle carrying cylinder and a needle carrying dial, the combination with a feeding guide for delivering substantially inelastic yarn to the needle hook of an auxiliary feeding guide adapted to deliver elastic thread along a circular line exterior to the cylinder needle Shanks in a position to be cast off with the loops formed by the cylinder needles, and a stitch forming center cam for the dial needles provided with a cam projection adapted to advance such needles over the cast off elastic thread immediately after it is moved over the associated cylinder needles to a position between the verge of the cylinder and the verge of the dial.

EGBERT FLEER. 

